Japan aims to beam solar energy down from orbit

Concept artwork shows how an array of mirrors could collect solar energy and transmit it to the ground

Mafic Studios, Inc

The Japanese space agency JAXA is developing a revolutionary
concept to put "power stations" in orbit to capture sunlight and
beam it to Earth.

The country has been looking for new power sources following the
devastating earthquake and tsunami in March, 2011, that destroyed
much of the north-east of the country and caused a meltdown at the
Fukushima Daiichi Nuclear Power Plant.

Many of the country's nuclear reactors were closed due to
stricter safety regulations after the emergency. Now JAXA
is aiming to set up a Space Solar Power System (SSPS) by 2030.
An array of mirrors would sit in geostationary orbit to collect
solar energy and then transmits it to a power plant on the ground
via microwaves or laser beams. There it could be used to generate
electricity and hydrogen.

Proponents of the technology say that it would provide
continuous energy without any worry that resources would be
depleted. It would be unaffected by the time of day or weather and
would provide environmentally friendly, clean energy.

Interestingly, the idea is not a new one. An American, Dr Peter
Glaser, designed a similar concept in 1968 to deploy large solar
panels in space to generate power and convert it into microwaves to
transmit to the ground. Following studies by NASA and the US
Department of Energy, the project was deemed too costly and it was
never developed.

Similar studies have been carried out in Europe. The idea is
also reminiscent of a Russian plan in the 1990s to use mirrors to
beam sunlight to the ground at night. This had astronomers and
environmentalists up in arms because of the light pollution it
would have caused. The Japanese concept is different because there
would be no stray light emitted from the beam.

Yasuyuki Fukumuro is leading research and planning for SSPS. He
says: "We have not yet decided whether to use microwaves or laser
beams with SSPS, or whether we will somehow combine them. We are
currently conducting ground-based experiments to find the most
efficient way to transmit energy.

"Regardless of which transmission technology we use, when we
collect sunlight from outside the Earth's atmosphere, we can get a
continuous supply of it, with almost no influence from the weather,
the seasons, or time of day, allowing very efficient collection of
solar energy.

"And since the energy source is the Sun, it's an endlessly
renewable resource -- it won't run out as long as the Sun is there.
Also, because the power is generated in space and carbon dioxide is
emitted only at the receiving site, emissions within the Earth's
atmosphere can be greatly reduced, which makes this technology very
friendly to the environment."

Fukumuro admits the system has its challenges. He says: "When
transmitting power by microwaves, a significant technological
challenge is how to control the direction, and transmit it with
pinpoint accuracy from a geostationary orbit to a receiving site on
the ground. Transmitting microwaves from an altitude of 36,000 km
to a flat surface 3 km in diameter will be like threading a
needle."

Fukumuro suggests the technology will also be useful in disaster
situations. In the event of a blackout, a collecting dish could be
unfolded and deployed to receive microwaves from space for
conversion into electrical energy.

JAXA is working with a collective of machining and engineering
companies called Kyoto Shisaku Net to develop the array of
reflectors that would be lifted into orbit by reusable shuttle-like
spacecraft and then assemble themselves.

JAXA Engineer and Senior Researcher Katsuto Kisara says: "The
biggest problem we've encountered with the project is developing
solar mirrors that are incredibly lightweight. I think that there
is certainly a way to do it, but it has presented quite the
challenge."

Original story appeared on (c) Sen. More space content from
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